The present invention relates to radio frequency identification (“RFID”) in safety applications, and in particular, to an RFID system for safely controlling an auto guided vehicle, an automated robot or other moving object (“AGV”).
RFID tags are typically used to detect the presence or identity of a physical object wherein an RFID tag is attached to the physical object. RFID tags may also be used to determine the location of a moving object in an RFID system wherein an RFID tag is attached to a stationary object at a particular location and detection of the RFID tag via an RFID transceiver on the moving object indicates proximity of the moving object to the stationary object at the particular location.
RFID tags are typically small, passive devices in which, upon coming into proximity of an electromagnetic field produced by an RFID transceiver or antenna, the RFID tag energizes and transmits via radio frequency waves data held in the RFID tag's memory. RFID tags often contain an unalterable, unique identification number at a particular memory location that is programmed during manufacturing, and a plurality of alterable memory locations for subsequent applications. Each memory location in the RFID tag may be read when energized by the RFID transceiver or antenna, and each alterable memory location in the RFID tag may be written and/or rewritten by the RFID transceiver or antenna until it is made unalterable by the RFID transceiver or antenna, or locked.
AGV's are typically used in field, warehouse, factory and industrial environments to accomplish certain tasks, such as moving objects from one location to another. AGV's may be guided by an electrical wire or track in the field, warehouse, factory or industrial environment or may be free running. To monitor if people are nearby and to avoid collisions, AGV's may utilize laser scanners which can detect, for example, people and objects in a 190° field around the AGV up to several meters away. In addition, the field, warehouse, factory or industrial environment may use safety edges in which the AGV stops if coming into contact. These methods offer some protection for people, but do not provide location based information.